- removed method plotAid, its functionality has been moved to other functions

- removed method plotAid, its functionality has been moved to other functions
- reduced the number of arguments in several methods
- the canvases are now created and filled inside the functions and under conditions
  that the respective THnSparse objects have non-zero entries
- the canvas with the overlaid histograms is created and filled only when there is more than one
  set of cuts to be studied
- added a canvas with overlaid track distributions for the offline tracks too
- took care of the way the statistics boxes are printed, now entries, mean and RMS appear